Steam generating unit



Jan. 13, 1970 E. c, MILLER 3,489,110

STEAM GENERATING UNIT Filed March 30, 1967 2 Sheets-Sheet l A .nv

EARLE C. MILLER INVENTOR.

BY .M

Jan. 13, 1970 E. c. MILLER STEAM GENERATING UNIT Z2 Sheets-Sheet 2 Filed March 30. 1967 FIG. 2

EARLE C. MILLER INVENTOR.

United States Patent O 3,489,110 STEAM GENERATING UNIT Earle C. Miller, Worcester, Mass., assgnor to Riley Stoker Corporation, Worcester, Mass., a corporation of Massachusetts Filed Mar. 30, 1967, Ser. No. 627,209 Int. Cl. F23r 1/18; F22b 33/00 U.S. Cl. 110-28 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a steam generating unit and, more particularly, to a steam generating unit capable of burning refuse solid fuel along with supplemental conventional fuels, and including a water-cooled bottom inclined at an angle greater than the angle of repose of the burned fuel and having a nose overlying it to direct refuse Onto the bottom.

BACKGROUND OF THE INVENTION There are many situations in industry where it is desirable to burn a refuse fuel not only to dispose of the refuse but also to make economic use of its heat of combustion. In such cases, it is usual practice to burn the refuse fuel in a furnace and to carry the hot products of combustion into heat exchange relationship with water in a broiler. The steam thus generated can be used in processing of the industry. An illustration of such a use is in the paper industry where a considerable amount of bark is removed from logs before the logs are converted into paper. The ba'rk must necessarily -be disposed of and, furthermore, large amounts of steam are necessary in the processing of the paper. It is an ideal combination, therefore, to burn the bark and to generate steam for th papermaking process. Many problems present themselves, however; for instance, the flow of refuse fuel is not a steady one and it is sometimes necessary to provide supplemental conventional fuels in the form of pulverized coal, oil, or gas. However, a furnace which is designed for burning a solid refuse fuel finds some difficulty in burning conventional fuels, and vice versa. These and other ditliculties experienced with the prior art devices have been obviated in a novel manner by the present invention.

OBJECTS It is, therefore, an outstanding object of the invention to provide a steam generating unit capable of burning refuse solid fuel and, at the same time, burning conventional fuels effectively.

Another object of this invention is the provision of a steam generating unit having a furnace With a novel method for disposing of ash.

A further object of the present invention is the provision of a steam generating unit in which the equipment for burning solid refuse, for burning conventional fuels,

and for disposing of the solid refuse are combined to giveI optimum operation of all elements.

It is another object of the instant invention to provide a steam generating unit for burning refuse fuels, which is simple in construction, readily operated, and capable of a long life of useful service with a minimum of maintenance.

It is a further object of the invention to provide a steam generating unit having an inexpensive means for burning refuse fuel and for disposing of the resulting ash.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

3,489,110 Patented Jan. 13, 1970 ICC The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings in which:

FIG. l is a side elevational view with portions broken away of a steam generating unit embodying the principles of the present invention,

FIG. 2 is a vertical sectional View of the unit taken on the line II-II of FIG. 1,

FIG. 3 is an enlarged sectional view of the unit taken on the line III-III of FIG. 2, and

FIG. 4 is a sectional view of the unit taken on the line IV-IV of FIG. 3.

Referring first to FIGS. 1 and 2, wherein are best shown the general features of the invention, the steam generating unit, indicated generally by the reference numeral 10, is shown as consisting of a furnace 11 and a boiler 12. The furnace has a front wall 13, a rear wall 14, two side walls 15 and 16, and a bottom 17. The bottom 17 consists of a plurality of spaced, inclined water tubes 18 which are covered with cast iron blocks 19. The furnace is provided with an ashpit 21 adjacent the front wall 13 and provided with conventional ash removal means 22. The front wall 13 of the furnace is covered with water-wall tubes in the usual manner and these are bent to form a nose 23 having a horizontal portion 24 overlying the ashpit 21 and an inclined portion 25 extending thereabove. The extension of the inclined portion 25, if continued in the imagination, would intersect the inclined surface of the bottom 17. The nose overlies the portion of the bottom 17 which is most closely adjacent to the ashpit 21.

The bottom 17 is provided with a steam system 26 for blowing ash down the incline of the bottom 17 into the ashpit 21. More specifically, the steam system consists of a plurality of nozzles 27 (see FIGS. 3 and 4) which extend through a large number of refractory blocks 19 and are directed toward the ashpit 21. The sides 15 and 16 of the furnace 11 are provided, respectively, with abutments 28 and 29 which, in turn, are provided with burners 31 and 32 for burning conventional fuel. These burners are of the directional-flame type shown and described in the patent of Miller, No. 3,203,463 issued Aug. 31, 1965. The front wall is provided for a feeder 33 for refuse fuel of the type shown and described in Patent No. 2,602,706 issued to Miller on July 8, 1952, this being in the form of a plurality of pneumatic spreaders. The feeder 33 is located above the nose 23 to project fuel onto the surface of the bottom 17 in such a Way that fuel falling on the surface 25 of the nose 23 will be directed onto the bottom 17 also. The bottom 17 is inclined at an angle which is less than the angle of repose of the fuel which, for the purposes of illustration, may be hogged bark.

The back wall 14 of the furnace 11 where it intersects the bottom 17 is provided with a plurality of nozzles 34 which are connected by suitable piping to a collection hopper 35 underlying the `boiler 12. A suitable pneumatic system is provided for carrying collected flyash from the hopper 35 to the nozzles 34 in the usual way.

OPERATION The operation of the invention will now be readily understood in view of the above description. Solid refuse fuel passes into the furnace 11 through the feeder 33, While a conventional fuel passes through the burners 31 and 32 into the furnace. The solid fuel is projected onto the cast iron blocks 19 forming an inclined surface for theI bottom 17 where burning takes place. Since the bottom is inclined at less than the angle of repose of the fuel, it will rest on the bottom without falling into the ashpit 21.

Occasionally, however, steam is introduced through the,y nozzles 27 and this steam creates a flow of the ash down the bottom into the ashpit 21 where it is disposed of by the ash removal means 22.

It can be seen, then, that, on occasions when the solid refuse fuel is available, a considerable amount of the hot products of combustion produced by the furnace will be produced by the burning of 'this refuse fuel on the bottom 17, and the ash will be suitably disposed of from time to time by use of the steam nozzles 27. When refuse fuel is not present in suicient quantities to produce the necessary products of combustion to -generate the amount of steam necessary for the operation of the paper making or other industrial uses, it may be necessary to introduce supplementary conventional fuel to the burners 31 and 32. Because of the fact that the abutments 28 and 29 overlie the. bottom of the furnace and that the auxiliary burners 31 and 32 are used, the furnace will have a very high temperature in the lower portion. This is particularly important where refuse fuel is being used because of the necssity of igniting and completely burning out the fuel. When incomplete combustion takes place, the stack effluent gas may carry considerable amounts of ash, resulting in an undesirable pollution of the atmosphere. Even when the collection system for the hopper 35 is fully effective, it is desirable to burn as much of the solid refuse fuel as is possible the first time through the furnace, since a large amount of return through the yash reinjection system to the nozzles 34 has an undesirable effect on the boiler operation and maintenance.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

I claim:

1. In a steam generating unit, a furnace for burning fuel to produce hot products of combustion, wall means enclosing said furnace, a bottom structure within said furnace, said bottom structure comprising an inclined support for maintaining refuse fuel during combustion, and an ashpit toward which said support inclines, said support cooperating with said wall means to define an opening leading down to said ashpit, nozzle means associated with said inclined support for blowing ash into said ashpit, and

means for supplying fluid to said nozzle means, a nose structure formed on said wall means to project inwardly of said furnace above said ashpit opening, said nose structure having an upper surface extending over and inclined toward said inclined support, and refuse fuel supply means arranged above said nose structure to project refuse material to be burned down onto the upper surface of said nose structure and said inclined support.

2. A steam generating unit according to claim 1 wherein said inclined support includes insulating blocks arranged to provide a smooth inclined surface and wherein said nozzle means comprises a plurality of conduits extending through the blocks and directed toward the ashpit.

3. A steam generating unit according to claim 1 wherein 'the inclined support has an angle of inclination less than the angle of repose of refuse fuel while the angle of inclination of the upper surface of said nose structure is greater than the angle of repose. of refuse fuel.

4. A steam generating unit according to claim 1 wherein said wall means includes a front wall, a back wall and side walls extending between said front and back walls, said inclined support extending from said back wall and inclined downwardly toward said front wall, inwardly directed' abutment structures formed on said side walls above said bottom structure, and burner means arranged to extend 'through said abutment means for burning fuel in suspension.

5. A steam generating unit according to claim 4 further including flyash collection means for recovering fiyash from said products of combustion and a pneumaticsystem arranged to direct the collected fiyash 'through said back wall and onto said inclined support.

References Cited UNITED STATES PATENTS 1,858,451 5/1932 Contant. 1,942,687 1/ 1934 Daniels. 2,057,450 10/1936 Schrenk 122-2 2,166,199 7/ 1939 Shoemaker. 2,185,865 1/1940 Myers.

CHARLES J. MYHRE, Primary Examiner U.S. Cl. X.R. 

